Field of the Disclosure
The disclosed subject matter relates generally to computing systems and, more particularly, to power management of a handheld processing device.
Description of the Related Art
Modern, high-performance processors include multiple heterogeneous processing units, such as central processing unit (CPU) cores and graphics processing unit (GPU) cores. Power management techniques are employed to allocate power adaptively across the processing units to produce the best performance outcome within a fixed processor power and thermal envelope.
The maximum power for a processing unit (i.e., the thermal design point (TDP)) is set based on running a heavy workload under worst-case conditions. The TDP represents an upper bound for sustainable power and is used to determine system cooling requirements to prevent the heat generated by the processing unit from damaging the components or reducing their service lifetimes.
In the case of handheld or wearable computing devices, such as tablet computers, mobile phones, smart watches, etc., the maximum operating temperature of a device is limited more by the perception of the user than by the silicon temperature limit. Heat generated by the processing units in the handheld device is conducted to the outer surfaces of the device, such as the display and the casing, where the user interfaces with the device during its operation. To provide the user with a comfortable experience, the maximum power budget allotted to the processing units is set at a fixed limit that could be less than the TDP to maintain the skin temperature of the device less than a value that the user would perceive as being too high.
The use of a static power limit is conservative and artificially reduces the performance of the device, because the static power limit is based on worst case skin temperature, i.e., a heavy workload for extended time period, while actual operating conditions do not often meet the worst case conditions.
The use of the same reference symbols in different drawings indicates similar or identical items.